Infectious diseases are usually caused by micro-organisms, such as bacteria, viruses, parasites, and fungi, and can transmit from one human to the next. This transmission can …occur via several routes (i.e. through contact with infectious droplets, or saliva, or blood or semen) which depend on the type and site of infection, but the main characteristic is they transmit from one person to the next.

Alzheimer's disease (AD) is an irreversible, progressive brain disease that slowly destroys memory and thinking skills and, eventually, the ability to carry out the simplest t…asks of daily living. In most people with AD, symptoms first appear after age 60. AD is the most common cause of dementia among older people, but it is not a normal part of aging. Dementia refers to a decline in cognitive function that interferes with daily life and activities. AD starts in a region of the brain that affects recent memory, then gradually spreads to other parts of the brain. Although treatment can slow the progression of AD and help manage its symptoms in some people, currently there is no cure for this devastating disease. AD is named after Dr. Alois Alzheimer, a German doctor. In 1906, Dr. Alzheimer described changes in the brain tissue of a woman who had died of an unusual mental illness. He found abnormal clumps (now called amyloid plaques) and tangled bundles of fibers (now called neurofibrillary tangles). Today, these plaques and tangles in the brain are considered hallmarks of AD. The third main feature of AD is the gradual loss of connections between nerve cells (neurons) in the brain. This loss leads to diminished cell function and cell death. We don't know what starts the AD process, but we do know that damage to the brain begins as many as 10 to 20 years before any obvious signs of forgetfulness appear. As nerve cells die throughout the brain, affected regions begin to shrink. By the final stage of AD, damage is widespread, and brain tissue has shrunk significantly.

This rare disease is a form of inflammation of blood vessels that appear most often with mucosalulceration and visual problems. The disease alsoaffects the digestive system, r…espiratory, muscular and nervous system. Can cause death from rupture of blood vessels and severe neurological complications, so treatment is an necessary.

A disease is any disturbance or anomaly in the normal functioning of the body that probably has a specific cause and identifiable symptoms..
Diseases are one of the factors …threatening us from having a properly functional life. Throughout our history, epidemics have caused the extinction of whole populations. Over the last century, man has discovered many microorganisms that cause diseases in humans and animals, and has learned how to protect himself from them, by either prevention or treatment..